Cannot add compiler option -O2 to the library / application

[mikelik]

How can I add compile options "-O2" to the project in antler?

When I try antler-proj update app XYZ C++ -O2 I get:
The following argument was not expected: -O2

I have also tried:

mikel@msi:~/repo/DUNE/tmp$ /home/mikel/repo/antler-proj/build/tools/antler-proj update lib  XYZ  C++ '-O2'
The following argument was not expected: -O2
Run with --help for more information.
mikel@msi:~/repo/DUNE/tmp$ /home/mikel/repo/antler-proj/build/tools/antler-proj update lib  XYZ  C++ "-O2"
The following argument was not expected: -O2
Run with --help for more information.

I have tried also \-O2.